MIMO(multiple-input multiple-output��radar can effectively improve radar performance by transmitting orthogonal signals. While the conventional single sequence can not keep the complete orthogonality (the sidelobes of the auto-correlation and cross-correlation function equal to zero at all delays). In the context of the problem, in conjunction with the property of the complete complementary sequence, the ambiguity function of complete complementary sequence was derived. The results of the computer simulations show that the validity of the proposed ambiguity function. The radar velocity resolution based on complete complementary sequence was also analyzed. The application of complete complementary sequence in MIMO radar was studied and the MIMO radar signal model based on complementary sequence was established. It is demonstrated that the complete complementary sequence has the potential to significantly improve the MIMO radar performance significantly. And the rationality and validity of the complete complementary sequence applied in MIMO radar are proved.